In recent years, with an increase in the population of the aged people, the number of aged patients having senile cataract has noticeably increased. The cataract is a disease in which a crystalline lens is opacified, and it induces a decrease in the vision depending upon the degree, region and site of the opacification and may sometimes deprive a patient of his or her eyesight. When a patient with cataract is treated, the opaque crystalline lens and cortex are removed and the vision is corrected with an ophthalmic lens or a contact lens, or an intraocular lens is inserted. It is a generally practiced method at present to remove the crystalline lens and then fix an intraocular lens in the capsule.
In the above method, however, remaining crystalline lens epithelial cells migrate into the posterior lens capsule and proliferate to generate opacification in the posterior capsule region, and the opacification may spread over the optic portion of the intraocular lens and may cause secondary cataract. For treating this secondary cataract after the insertion of an intraocular lens, there is employed a method in which the opacified portion is removed by irradiation with an ND:YAG laser beam. However, this method has defects that the apparatus therefor is expensive and that the fundus examination, photocoagulation and vitreous body operation are hampered (for example, see NISHI Okihiro, et al., “Secondary Cataract Inhibiting Effect of Intraocular Lens”, Summary of the 15th Europe Intraocular Lens Society Conference, 1997).
As other method, there are known a method of treating and preventing secondary cataract by using a medicine (for example, see JP-A-9-291040), a method of forming an intraocular lens whose circumferential portion has sharp edges to inhibit the secondary cataract (for example, see the above Summary of the 15th Europe Intraocular Lens Society Conference) and a method of coating that portion of an intraocular lens which corresponds to the posterior capsule portion with a biocompatible material having a specific composition (for example, see Japanese Translation Version No. 2002-511315 of PCT Application).
The above methods have an effect on the inhibition of secondary cataract to some extent. However, they have problems that it is required to organize a new combination of an intraocular lens and a medicine and that additional precision-processing is required for finishing a sharp circumferential portion. It has been therefore desired to develop a process for further simply producing an intraocular lens capable of inhibiting secondary cataract.